The invention relates to a filter tube for drain purposes, provided with openings debouching at its outer surface, said openings being adapted to be connected to a sub-atmospheric source through at least one discharge channel in the tube.
According to a known method a hole is flushed in the ground by means of a flush-water pipe, whereafter a filter tube is positioned in this hole.
According to another known method a casing closed at the upper side by means of a screw cap and open at its lower side is connected to a source of a pressure fluid, such as water or air under pressure, whereafter this casing is flushed into the ground. Hereupon the screw cap of the casing is removed and a filter tube is positioned within the casing, whereafter the casing is lifted again, while the filter tube remains in the ground.
These known methods for positioning a filter tube in the ground have the disadvantage that a relatively large number of steps has to be taken, which are time consuming and costly.